The DS3231M is a low-cost, extremely accurate, I2C real-time clock (RTC). The device incorporates a battery input and maintains accurate timekeeping when main power to the device is interrupted. The integration of the microelectromechanical systems (MEMS) resonator enhances the long-term accuracy of the device and reduces the piece-part count in a manufacturing line. The DS3231M is available in the same footprint as the popular DS3231 RTC.

The RTC maintains seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12-hour format with an active-low AM/PM indicator. Two programmable time-of-day alarms and a 1Hz output are provided. Address and data are transferred serially through an I2C bidirectional bus. A precision temperature-compensated voltage reference and comparator circuit monitors the status of VCC to detect power failures, to provide a reset output, and to automatically switch to the backup supply when necessary. Additionally, the active-low RST pin is monitored as a pushbutton input for generating a microprocessor reset. See the Block Diagram in the full data sheet for more details.